Allow customizing container image path used in NVIDIA GPU addon. (#4229)

roles/kubernetes-apps/container_engine_accelerator/nvidia_gpu/templates/k8s-device-plugin-nvidia-daemonset.yml.j2

@@ -38,7 +38,7 @@ spec:
         hostPath:
           path: /dev
       containers:
-      - image: "k8s.gcr.io/nvidia-gpu-device-plugin@sha256:0842734032018be107fa2490c98156992911e3e1f2a21e059ff0105b07dd8e9e"
+      - image: "{{ nvidia_gpu_device_plugin_container }}"
         command: ["/usr/bin/nvidia-gpu-device-plugin", "-logtostderr"]
         name: nvidia-gpu-device-plugin
         resources:

roles/kubernetes-apps/container_engine_accelerator/nvidia_gpu/templates/nvidia-driver-install-daemonset.yml.j2

@@ -48,7 +48,7 @@ spec:
         hostPath:
           path: /
       initContainers:
-      - image: "{{nvidia_driver_install_container}}"
+      - image: "{{ nvidia_driver_install_container }}"
         name: nvidia-driver-installer
         resources:
           requests:
@@ -63,9 +63,9 @@ spec:
           - name: ROOT_MOUNT_DIR
             value: /root
           - name: NVIDIA_DRIVER_VERSION
-            value: "{{nvidia_driver_version}}"
+            value: "{{ nvidia_driver_version }}"
           - name: NVIDIA_DRIVER_DOWNLOAD_URL
-            value: "{{nvidia_driver_download_url_default}}"
+            value: "{{ nvidia_driver_download_url_default }}"
         volumeMounts:
         - name: nvidia-install-dir-host
           mountPath: /usr/local/nvidia
@@ -74,5 +74,5 @@ spec:
         - name: root-mount
           mountPath: /root
       containers:
-      - image: "gcr.io/google-containers/pause:2.0"
+      - image: "{{ pod_infra_image_repo }}"
         name: pause